This disclosure relates generally to photoreceptor devices and, in particular, to an apparatus and method for coating photoreceptor devices.
It is known to use diptanks to apply photoreceptor coating solution to photoreceptor devices. It is further known to use a manifold to supply the photoreceptor solution to the diptanks so the photoreceptor devices, which are cylindrical-shaped, may be coated therein.
Typically, a manifold is arranged to supply photoreceptor coating solution to multiple diptanks. As a result of the manifold, photoreceptor coating solution is caused to flow in each diptank of the multiple diptanks. Photoreceptor devices are then dipped into the diptanks.
Once inserted in the diptanks, the devices will be removed from the diptank with a controlled speed, and a thin layer of photoreceptor coating solution becomes coated upon each device.
During this coating process, it is very important that the overflow of the photoreceptor coating solution in every diptank be uniform and the same amount.
To increase process yield, the manifold is equipped with many diptanks, thus allowing a like number of devices to be coated at the same time. With a large number of devices being coated simultaneously, the problem is how to obtain uniform coating results with respect to charge generator layer coating thickness and other electrical specifications for all devices in the same batch. In other words, the goal is to simultaneously coat multiple photoreceptor devices, wherein each device is coated identically to each other device in the same batch.
One key to obtaining identical coating results for all devices in the same coating batch is to maintain identical flows and overflow of photoreceptor coating solution in each diptank during the coating process.
With existing photoreceptor coating arrangements, the multiple diptanks are supplied by manifolds with a uniform diameter along the flow direction. As a result of multiple diptanks being supplied by constant-diameter manifolds, the coating solution flow speeds varies substantially from diptank to diptank. As a result of varying coating solution flow speeds, the coating process likewise varies substantially from diptank to diptank.
With this existing constant-diameter manifold approach, for diptanks located substantially xe2x80x9cupstreamxe2x80x9d or xe2x80x9cdownstreamxe2x80x9d along the manifold flow direction from each other, the coating results are especially non-uniform. This is because the manifold""s coating solution flow speed varies along the manifold""s length as it supplies the multiple diptanks spaced along the length. Moreover, this constant-diameter manifold approach results in multiple devices being coated with their individual coating layers being substantially different.
Another problem with this existing constant-diameter manifold approach is that the diptank needs to be placed out of level to maintain an equal overflow on all the diptanks, even though this will result in other defects and unequal non-coated areas on the devices.
It is thus desirable to provide an apparatus and method for coating photoreceptor devices in multiple diptanks that will provide for the photoreceptor coating solution flow speed in each diptank of the multiple diptanks to be the same.
Therefore, there is a need for an improved apparatus and method for coating photoreceptor devices.
In one aspect of the invention, there is provided an apparatus for coating devices. The apparatus comprises a manifold forming a conduit, the conduit having a length with an input at one end thereof. The apparatus further comprises a plurality of diptanks mounted on an upper portion of the manifold and distributed along the length. The plurality of diptanks are arranged for applying coating solution to devices that are dipped therein. The conduit is arranged so that coating solution supplied to the input flows to the plurality of diptanks, thus forming therein a plurality of diptank coating solution flows. The conduit becomes increasingly narrower as the coating solution flows along the length successively from one diptank to the next diptank of the plurality of diptanks. As a result, the plurality of flow speeds of the corresponding plurality of diptank coating solution flows are substantially uniform.
In another aspect of the invention, there is provided an apparatus for coating devices. The apparatus comprises a manifold forming a conduit, the conduit having a length with an input at one end thereof. The apparatus further comprises a plurality of diptanks mounted on an upper portion of the manifold and distributed along the length, the plurality of diptanks being arranged for applying coating solution to devices dipped therein. The conduit is arranged so that coating solution supplied to the input flows to the plurality of diptanks thus forming a diptank coating solution flow with a corresponding diptank coating solution flow speed in each of the plurality of diptanks. The conduit is wedge-shaped along the length, thereby causing each of the plurality of diptank coating solution flow speeds to be substantially equal with respect to each other.
In another aspect of the invention, there is provided a method for coating devices using an apparatus. The apparatus comprises a manifold forming a conduit, the conduit having a length with an input at one end thereof. The apparatus further comprises a plurality of diptanks mounted on an upper portion of the manifold and distributed along the length. The plurality of diptanks are arranged for applying coating solution to devices that are dipped therein. The conduit is arranged so that coating solution supplied to the input flows to the plurality of diptanks, thus forming therein a plurality of diptank coating solution flows. The conduit becomes increasingly narrower as the coating solution flows along the length successively from one diptank to the next diptank of the plurality of diptanks. As a result, the plurality of flow speeds of the corresponding plurality of diptank coating solution flows are substantially uniform. The method comprises the steps of: a supplying coating solution to the input, and b dipping devices into the plurality of diptanks, thereby applying coating solution to the devices.